This invention relates method for treating waste material containing organic matter and potentially toxic levels of certain contaminants, such as heavy metals.
Waste material or effluent which contains organic materials, such as that from intensive animal farming operations, food processing plants and city sewage, constitutes a serious problem in that in large quantities the material is toxic and in that the material can give off noxious fumes. Disposal of such materials is therefore difficult and the development of such materials from the operation can inhibit the installation of new plants to carry out such processing.
Usually such waste material is stored in a lagoon which is simply a hollowed open area into which the material is pumped to allow settling of the solid matter to the bottom of the lagoon and dispersal of the liquid and gas content by evaporation. Periodically it is necessary to remove the settled solids and these are often simply dumped into an open field. The continuous evaporation of the liquid acts to discharge into the air noxious gases which leads to environmental pollution which is becoming politically unacceptable. The lagoon can also leak so as to cause contamination of the ground water.
A serious problem which arises with the discharge of materials of this type is that of the noxious or bad smelling fumes that are emitted by the anaerobic bacteria acting upon the nitrogen compounds of the waste materials. Such fumes arise wide public outcry in the event that such waste materials are dumped onto the ground in locations anywhere near any housing developments.
It is known to use an oxidizing agent, such as hydrogen peroxide, on liquid manure to destroy the anaerobic bacteria to reduce release of noxious gases.
However, simply treating the waste material so as to limit smell is insufficient to make dumping on an open field acceptable. This is because waste material often contains contaminants such as heavy metals in potentially toxic doses, a problem that is even more pronounced in city sewage. When this type of waste material is applied to an open field, the heavy metals will contaminate the soil and possibly the groundwater. This poses a significant health risk if the contaminated soil or groundwater is used for growing food crops as the heavy metals will be taken up by growing plants. As a consequence, there are restrictions on the per acre concentration of heavy metals permittable in disposed waste material. Obviously, there cannot be an infinite supply of land available for this purpose. Given the large amount of waste generated by a city of even medium size, disposal of civic sewage is clearly a growing and costly problem.
One machine for spreading waste material from hog barns and the like onto ground includes a frame with ground wheels for moving across the ground, the frame carrying a reel on which is wound a pipe for transporting the waste material from a supply. From the reel the waste material is communicated to a spray gun or spreader which discharges the material across the ground. This type of discharge of the material is unacceptable in that it generates smell, loses nitrogen which could otherwise be available for crop growth and also can release airborne bacteria which is dangerous to health.
An alternative type of machine for carrying out disposal of waste material includes a tank which transports the material to the required location and a spray boom for discharging the material onto the ground. Generally such processes are used simply for disposal of the waste material without any other advantages being considered or expected. The waste material is thus collected from a lagoon or storage container and is simply dumped into the field in a manner which is intended simply to dispose of the material. In many cases this is done in a relatively remote location with high quantities of the material being discharged into the field simply as a disposal process. The use of a tank to transport the material is basically unacceptable for larger quantities of the material in view of the very heavy weights of such a large tank which causes compaction of the ground over which the transport vehicle travels and the repeated trips which are necessary to dispose of all of the material. A machine of this type therefore is really only suitable for relatively small quantities of waste material to be discharged.
One example of a machine for dumping manure from hog barns is shown in article entitled "Fertilisation du lisier sur ble".
A brochure by Bauer entitled "Boom Cart AS45" shows a machine for irrigation which includes a reel cart and a boom assembly separate from the reel cart. The boom assembly is moved along a strip to be irrigated away from the reel cart and pulls a pipe from the reel. The boom assembly then moves along the strip of ground to be irrigated and water is pumped through the pipe to the boom. This arrangement is however not in any way proposed for discharging manure or other waste materials.
A further arrangement is known comprising a vehicle having a reel drum which is carried on the vehicle and supplies manure through a pipe line paid out from the reel to a jet nozzle carried on the vehicle for discharging waste materials onto the ground.